Friction clutch



FIG. I.

H, l. CROW FRICTION CLUTCH Filed Aug. 9, 1944 2 Sheets-Sheet I INVENTOR. HAROLD I. CROW KMQIM Aprfl W, 1M5. H. I. CROW 293739462 FRICTION CLUTCH Filed Aug. 9, 1944 2 Sheets-Sheet 2 INVENTOR.

HAROLD C ROW HTTOIPNEY Fig. 1; and

,Figs. 3 and 4 are diagrammatical illustrations- Patent ed Apr. 10, 1945 UNITED STATES PATENT 1 OFFICE 2.37am r I rnrc'rroucmron .Harold I. Grow, Radburn, N. J., assignor to Associates, Incorporated, Teterboro, N. J a cor-' poration of New York Application August 9. 1944, Serial No. 548,723

Claims. (Cl. 192-41) The invention relates to an automatic clutch and more particularly to a friction clutch of the type wherein engagement and disengagement takes place according to the starting and stopping of the driving element. The invention oon-' other object of the invention is the provision of means to insure prompt disengagement of the clutch when the driving element is decelerated.

The invention consists of inertia means effective to initiate the clutching operation in combination with other means for positively locking the clutching elements in engaged position as long as a driving torque prevails. In addition thereto means may be provided to store, during acceleration of the driving part, a force which may be released upon deceleration to facilitate the disengagement of the clutching elements.

Further objects and details of the invention will be apparent from the description given here inafter and the accompanying drawings illustrating an embodiment thereof'by way of, example.

In the drawings,

Fig. 1 is-a longitudinal section of a clutch mechanism according to my invention, taken along line ll of Fig. 2; V

Fig. 2 is a cross-section along line of the relative. shifting of the parts during a clutching operation.

Referring now to the drawings, the clutch comprises a rotatable input shaft i, shown in Fig. 1 as supported by two bearings 2 and 3. An inertia mass such as disc 4 with hub 5 is carried by shaft I through the intermediary of an anti-friction needle bearing 6. studs 1 and 8 are secured to the disc 4 so as to project forward from the front face 9 thereof. The studs hold each a coupling. shoe, Iii-and Ii respectively; however, the diameters of the holes l2 and i3 in the shoes through which the studs pass, are larger than those of the portions ll of the studs interiorly of said holes. Nuts IS with washers iii are provided on the free ends of the studs in order to prevent movement of the shoes in an axial direction,but do not restrain the shoes from moving relatively to the studs as far as the oversize of the holes l2 and it permits. The shoes are substantially of segment shape with faces I! and I8 respectively constituting the chords of the varcuate faces which are provided with linings ill of suitable frictional material. Two springs and 2i at opposite ends of the shoes engage the latter in holes 22 and tend to pull them towards each other, that is to say, against the faces 23 and 24 of acam 25,

which may be, as in the present case, of substantially rectangular shape or of another suitable configuration, and which is secured to or integral with shaft l. The faces 23 and 24 con? stitute the longer sides of the rectangular cam contour, the length of the shorter sides 26 and I 21 being approximately equal to the shaft diam- Two diametrically opposite eter. A drum 28 with inner cylindrical face 29 surrounds the shoes i0 and I i and also the disc 4. The 'drum is mounted withits hub 30 on a needle bearing 3i carried by'the shaft I, so that the drum can freely turn in relation to the shaft. Washers 50, 5| and 52 may be inserted between eachtwo of the parts 2, 30, 4 and 25, respectively, in order to reduce any occurring friction. Hub- 30 embodies means to con nect the drum :0 to a device intended to be driven by shaft i through the intermediary of the clutch members just described. In the case of the illustrated embodiment, where the shaftis supported by an outside bearing 2, the mentioned means may consist in gear teeth 33 for the engagement of another gear. If the general structure is such that no outside bearing 2 is required, the hub 30 may be directly connected to the portions id of the studs 1 and 8 will come to restraint of the springs into the position of Fig.

4, in which they engage the drum 28. This effect of the disc on the shoes will be assisted also by f the inertia of the shoes acting in the same direction as the inertia of the disc. Owing to the 2 retarding effect of friction between the and the shoes, the inner, faces I! and I8 of the asrasea nected' driven parts. so that spring SI will be shoes will now be at an angle to the cam faces 23 and 24 respectively, and the cam corners 60' and GI will now\'bear against the faces I! andid to, lock the shoes frictionally to the drum 28 so that the drum 28 and disc I are taken along synchronously with shaft I. If shaft I is decelerated,- the reverse action occurs. The cam corners 60 and BI will slide along the shoe faces I1 and I 8 respectively while the inertia "of disc 4 will cause a relative shift so that the stud portions Il come to bear against the opposite points of the holes I2 and I3, thereby causing a moment turning the shoes wtih their faces I I and I8 into engagement with the cam faces and 24 and with their arcuate faces out of engagement with the drum. The springs 20 and ii help in the same direction, so that there is no more friction during the time the drum 28 continues to overrun shaft I..

The clutch hereinbefore described operates in general very satisfactorily in response to the accelerations and decelerations of the shaft I.

However, I have found that in: certain instances,

, the shoes do not quite readily separate from the drum. In this connection it is to be considered that the force of springs 20 and 2| must be correctly selected according to the inertia I of the disc 4, and cannot be very, strong if it is the intention to do with a reasonably small.

inertia mass. The force of the springs and 5 2|, best suited to the purpose, can be easily ascertained by trial. It may happen, therefore,

that there still remains friction between the parts or that the clutch stays even fully engaged during aitime when no driving torque is transm'itted.

1 Such conditions mayprevail for instance, if I shaft I is coupled to therotor of a prime mover and if, then the power of the prime mover is shut oil and, more or less, suddenly, a braking force is applied to the drum and/or to the parts driven'byit. In that event; shaft I may tend to overrun the drum owing to its inertia and that of the rotor of the primemover. In consequence, the cam will remain in its position of Fig. 4 relatively to the shoes I0 and II during the deceleration period and even after all parts have come to a standstill. when, then,

the shaft 1 is started again, the desired inertia eil'ect of the clutch could not occur and the latter would function similarly to a positive coupling. To prevent the occurrence of such drawback, I provide means whereby a force 5 man be stored during the time a driving torque is transmitted, i. e. while shaftI overruns drum 28, such force to be released when the driving power is shut off, in order to create a torque reversing the driving shaft and, thereby restoring the parts to their relative position of Fig. 2.

For this purpose, shaft I isnot directly ,con-

nected to a drive shaft of a prime mover, but

by a torsion spring 3b secured with its ends -86 and 81 to two sleeves 38 and 39 respectively. The sleeves are interiorly splined at l4 and and provided with flanges l0 and II which are recessed at 42 and 43 to anchor therein the mentioned endsof the spring. Sleeve'll is thus secured to the free end 48 of shaft I. whereas sleeve 39 may be secured to a prime mover shaft 48, supported by a bearing 01 in coaxial alignment with shaft I. If now, shaft 0 starts to rotate a resistant torque will be set up first by the inertia disc and, then, additionally same direction as the aforementioned driving torque. As soon. however, as the parts come to a standstill, that means when the torque owing f to the braking disappears, the torsion of the spring" will be released to turn shaft I backwards sufllciently to restore the parts totheir original relative position. Other spring arrangements are of course also possible whereby the desired result may be obtained, it being'necesq sary only that such spring or springs are operatlve to store during a driving period, a force which can be released to cause a torque reversing the cam shaft when rotation of the system is stopped. It will be apparent to those skilled in the art that many alterations and modifications of the mechanism illustrated and described are possible without departing from the spirit and essence of my invention which for this reason-shall be .limited only by the scope of the appended claims.

I claim:

1. In a friction clutch including a, cam-provid-' ed input member, an output member and clutch shoes operable by said cam to frictionally couple said input member to said output member, the

combination ofan inertia'mass in coaxial arrangement with said input and output members, said mass being free to turn a limited angle in relation to said input member and being floatingly connected to said shoes for a limited movement in relation thereto so as to cause an initialfrictional engagement of said shoes and said output member when lagging in relation to said input member upon an acceleration of the latter, and a torque-storing means secured to said input member and adapted to connect said input member to a prime mover shaft for rotation.

2. A clutch comprising a rotatable input member, a drum-shaped output member, an inertia mass in coaxial arrangement with said input and output members and free to-turn a limited angle in relation to said input member, a pair of segment-shaped clutch shoes adapted for frictional engagement with said drum and floatingly anchored to said inertia mass for a limited movement in relation thereto, a cam secured to said input member between said shoes so as to pressthem against said drum upon an angular movementof said input member relatively to said shoes, resilient means attached to both shoes and tending to pull them towards each other, and a,

torque-storin means secured to said input member and adapted to connect said input member to a prime mover shaft for rotation.

h 3. A clutch comprising a rotatable input member, a drum-shaped output member, an inertia mass in coaxial arrangement with said input and output members and free to turn a limited angle in relation to said input member, a pair of segment-shaped clutch shoes adapted for frictional engagement with said drum and floatingly anchored to said inertia mass for a limited movement in relation thereto, a cam secured to said input member between said shoes so as to press them against said drum upon an angular moveheroment of said input member relatively to said shoes, resilient means attached to both shoes and tending to pull them towards each other, and resilient means secured to said input member and adapted to connect said input member to a prime mover shaft so as to transmit driving power from the prime mover to said input member and to store energy during a driving period for a short angular reversal of the input member at the end of such period.

4. In a friction clutch including a cam-privided input member, an output member and clutch shoes operatable by said cam to frictionally couple said input member to said output member, the combination of an inertia mass in co-axial arrangement with said input and output members, said mass being free to turn a limited angle in relation to said input member, and being floatingly connected to said shoes for a limited movement in relation thereto so as to cause an initial frictional engagement of said shoes and said output memberwhen lagging in relation to said input member upon an acceleration of the latter, a torsion spring secured with one of its end to said input member, and means secured to the other end of said torsion spring to connect it to a prime mover shaft.

5. A clutch'comprising a rotatable input member, a drum-shaped output member, an inertia mass in coaxial arrangement with said input and output members and free to turn a limited angle in relation to said input members, a pair of segment-shaped clutch shoes adapted for frictional engagement with said drum and floatingly anchored to said inertia mass for a limited movement in relation thereto, a cam secured to said input member between said shoes so as to press them against said drum upon an angular movement of said input member relatively to said shoes, resilient means attached to both shoes and tending to pull them towards each other, a torsion spring secured with one of its ends to said input member, and means secured to the other end of said torsion spring to connect it to a prime mover shaft.

HAROLD I. CROW. 

